WEDNESDAY, Dec. 14, 2016 (HealthDay News) -- The prices of brand-name drugs used by many older Americans rose nearly 130 times faster than inflation last year, a new study reports.

"This new report once again highlights the high and unrelenting price increases that are shockingly common in the pharmaceutical market," said Debra Whitman. She is chief public policy officer at AARP, a nonprofit organization focused on social welfare issues.

"What's particularly remarkable is that these incredibly high price increases are still occurring in the face of the intense public and congressional criticism of prescription drug pricing practices," Whitman said in an AARP news release.

The researchers examined the prices of 268 brand-name prescription drugs widely used by seniors, including 49 in drug categories that are used to treat common and often chronic conditions, such as high blood pressure, high cholesterol and diabetes.

The retail prices of the drugs rose an average of 15.5 percent in 2015, compared with a 0.1 percent increase in the general inflation rate, according to the AARP report.

The study findings also showed the average annual cost for chronic use of one brand-name drug rose to more than $5,800, compared with nearly $1,800 in 2006.

The average older person takes 4.5 prescription drugs a month. This means that current average yearly drug costs could be as much as $26,000, the researchers suggested.

The average median income of Medicare beneficiaries is $24,150.

The drug prices in the report are the total costs, and may not represent the actual out-of-pocket costs that a Medicare patient would pay at the pharmacy, the report authors noted.

Of the 268 drugs included in the report, 97 percent had retail price increases in 2015. Seven had average price increases of more than 50 percent. Five of the six drugs with the highest price increases were marketed by Valeant Pharmaceuticals. The price of the company's anti-anxiety drug Ativan rose over 2,800 percent between 2006 and 2015, the study authors said.

Report co-author Leigh Purvis said that "prescription drug therapy is not affordable when its cost exceeds the patient's entire income." Purvis is director of health services research at the AARP Public Policy Institute.

"Even if patients are fortunate enough to have good health care coverage, high prescription drug costs translate into higher out-of-pocket costs -- especially for those who pay a percentage of drug costs rather than a fixed co-payment -- as well as higher premiums, deductibles and other forms of cost-sharing," Purvis said.